CHAPTER 3: INSTALLATION
DIRECT INPUT AND OUTPUT COMMUNICATIONS
N60 NETWORK STABILITY AND SYNCHROPHASOR MEASUREMENT SYSTEM – INSTRUCTION MANUAL
3-35
3
Figure 3-36: G.703 timing selection switch setting
Table 3-6: G.703 timing selections
3.4.4.3 G.703 octet timing
If octet timing is enabled (ON), this 8 kHz signal is asserted during the violation of bit 8 (LSB) necessary for connecting to
higher order systems. When N60s are connected back-to-back, octet timing is disabled (OFF).
3.4.4.4 G.703 timing modes
There are two timing modes for the G.703 module: internal timing mode and loop timing mode (default).
•
Internal Timing Mode
— The system clock is generated internally. Therefore, set the G.703 timing selection to internal
timing mode for back-to-back (UR-to-UR) connections. For back-to-back connections, set octet timing (S1 = OFF) and
timing mode to internal timing (S5 = ON and S6 = OFF).
•
Loop Timing Mode
— The system clock is derived from the received line signal. Therefore, set the G.703 timing
selection to loop timing mode for connections to higher order systems. For connection to a higher order system (UR-
to-multiplexer, factory defaults), set to octet timing (S1 = ON) and set timing mode to loop timing (S5 = OFF and S6 =
OFF).
The switch settings for the internal and loop timing modes are shown.
Switches
Function
S1
OFF
→
octet timing disabled
ON
→
octet timing 8 kHz
S5 and S6
S5 = OFF and S6 = OFF
→
loop timing mode
S5 = ON and S6 = OFF
→
internal timing mode
S5 = OFF and S6 = ON
→
minimum remote loopback mode
S5 = ON and S6 = ON
→
dual loopback mode
